title: Enhanced stability and knockdown efficiency of poly(ethylene glycol)-b-polyphosphoramidate/siRNA micellar nanoparticles by co-condensation with sodium triphosphate.
abstract: OBJECTIVE
  Polyelectrolyte complex nanoparticles are a promising vehicle for siRNA delivery but suffer from low stability under physiological conditions. An effective stabilization method is essential for the success of polycationic nanoparticle-mediated siRNA delivery. In this study, sodium triphosphate (TPP), an ionic crosslinking agent, is used to stabilize siRNA-containing nanoparticles by co-condensation.
  
  
  METHODS
  siRNA and TPP were co-encapsulated into a block copolymer, poly(ethylene glycol)-b-polyphosphoramidate (PEG-b-PPA), to form ternary nanoparticles. Physicochemical characterization was performed by dynamic light scattering and gel electrophoresis. Gene silencing efficiency in cell lines was assessed by dual luciferase assay system.
  
  
  RESULTS
  The PEG-b-PPA/siRNA/TPP ternary nanoparticles exhibited high uniformity with smaller size (80-100 nm) compared with PEG-b-PPA/siRNA nanoparticles and showed increased stability in physiological ionic strength and serum-containing medium, due to the stabilization effect from ionic crosslinks between negatively charged TPP and cationic PPA segment. Transfection and gene silencing efficiency of the TPP-crosslinked nanoparticles were markedly improved over PEG-b-PPA/siRNA complexes in serum-containing medium. No significant difference in cell viability was observed between nanoparticles prepared with and without TPP co-condensation.
  
  
  CONCLUSIONS
  These results demonstrated the effectiveness of TPP co-condensation in compacting polycation/siRNA nanoparticles, improving nanoparticle stability and enhancing the transfection and knockdown efficiency in serum-containing medium.
authors.affiliation: Department of Materials Science and Engineering Johns Hopkins University Baltimore, Maryland 21218, USA Translational Tissue Engineering Center, Johns Hopkins University Baltimore, Maryland 21218, USA Department of Biomedical Engineering, Johns Hopkins University Baltimore, Maryland 21218, USA Department of Neuroscience, Johns Hopkins University Baltimore, Maryland 21218, USA Whitaker Biomedical Engineering Institute, Johns Hopkins University Baltimore, Maryland 21218, USA 101E Maryland Hall, 3400 North Charles Street Baltimore, Maryland 21218, USA.
authors.forename: Masataka
authors.initials: M
authors.lastname: Nakanishi
authors.affiliation: Department of Materials Science and Engineering Johns Hopkins University Baltimore, Maryland 21218, USA Translational Tissue Engineering Center, Johns Hopkins University Baltimore, Maryland 21218, USA Department of Biomedical Engineering, Johns Hopkins University Baltimore, Maryland 21218, USA Department of Neuroscience, Johns Hopkins University Baltimore, Maryland 21218, USA Whitaker Biomedical Engineering Institute, Johns Hopkins University Baltimore, Maryland 21218, USA 101E Maryland Hall, 3400 North Charles Street Baltimore, Maryland 21218, USA.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Patil
authors.affiliation: Department of Materials Science and Engineering Johns Hopkins University Baltimore, Maryland 21218, USA Translational Tissue Engineering Center, Johns Hopkins University Baltimore, Maryland 21218, USA Department of Biomedical Engineering, Johns Hopkins University Baltimore, Maryland 21218, USA Department of Neuroscience, Johns Hopkins University Baltimore, Maryland 21218, USA Whitaker Biomedical Engineering Institute, Johns Hopkins University Baltimore, Maryland 21218, USA 101E Maryland Hall, 3400 North Charles Street Baltimore, Maryland 21218, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Ren
authors.affiliation: Department of Materials Science and Engineering Johns Hopkins University Baltimore, Maryland 21218, USA Translational Tissue Engineering Center, Johns Hopkins University Baltimore, Maryland 21218, USA Department of Biomedical Engineering, Johns Hopkins University Baltimore, Maryland 21218, USA Department of Neuroscience, Johns Hopkins University Baltimore, Maryland 21218, USA Whitaker Biomedical Engineering Institute, Johns Hopkins University Baltimore, Maryland 21218, USA 101E Maryland Hall, 3400 North Charles Street Baltimore, Maryland 21218, USA.
authors.forename: Rishab
authors.initials: R
authors.lastname: Shyam
authors.affiliation: Department of Materials Science and Engineering Johns Hopkins University Baltimore, Maryland 21218, USA Translational Tissue Engineering Center, Johns Hopkins University Baltimore, Maryland 21218, USA Department of Biomedical Engineering, Johns Hopkins University Baltimore, Maryland 21218, USA Department of Neuroscience, Johns Hopkins University Baltimore, Maryland 21218, USA Whitaker Biomedical Engineering Institute, Johns Hopkins University Baltimore, Maryland 21218, USA 101E Maryland Hall, 3400 North Charles Street Baltimore, Maryland 21218, USA.
authors.forename: Philip
authors.initials: P
authors.lastname: Wong
authors.affiliation: Department of Materials Science and Engineering Johns Hopkins University Baltimore, Maryland 21218, USA Translational Tissue Engineering Center, Johns Hopkins University Baltimore, Maryland 21218, USA Department of Biomedical Engineering, Johns Hopkins University Baltimore, Maryland 21218, USA Department of Neuroscience, Johns Hopkins University Baltimore, Maryland 21218, USA Whitaker Biomedical Engineering Institute, Johns Hopkins University Baltimore, Maryland 21218, USA 101E Maryland Hall, 3400 North Charles Street Baltimore, Maryland 21218, USA.
authors.forename: Hai Quan
authors.initials: HQ
authors.lastname: Mao
mesh_terms: D000577:Amides / Q000737:chemistry*; D000838:Anions; D002470:Cell Survival; D004355:Drug Stability; D020868:Gene Silencing; D006367:HeLa Cells; D006801:Humans; D008823:Micelles; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D010756:Phosphoric Acids / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011122:Polyphosphates / Q000737:chemistry*; D034741:RNA, Small Interfering / Q000235:genetics*
chemical_list: D000577:Amides; D000838:Anions; D008823:Micelles; D010756:Phosphoric Acids; D011122:Polyphosphates; D034741:RNA, Small Interfering; D011092:Polyethylene Glycols; C011067:phosphoramidic acid; C005692:triphosphoric acid